Ionic actuators based on novel sulfonated ethylene vinyl alcohol copolymer membranes

Suffonated ethylene vinyl alcohol copolymers have been synthesized and artificial muscles have been produced from this new class of ionomeric membrane materials. FTIR spectroscopy confirmed the modification through introduction of peaks characteristic of ester linkages between sulfosuccinic acid and vinyl alcohol. Solid-state Na-23 NMR showed the ionic functionalities aggregate during membrane casting, yet small angle X-ray scattering showed that nano-phase separation between the ionic domains and matrix occurs only at elevated sulfonate content. Ionic polymer metal composites were produced through an electroless deposition of platinum generating membranes that display actuation under applied electrical stimulus. The perfluorosulfonate ionomer Nafion (R) has been used as a benchmark to gauge the performance of the artificial muscles produced in this study. Results showed the modified EVOH IPNIC's behave similar to Nation yet actuation kinetics in the new ionomer are significantly slower. Pulsed gradient spin echo NMR showed water diffusion coefficients in modified EVOH to be 1/3 those in Nafion (R) though the water content in the new ionomer is more than double. Slower actuation kinetics are, therefore, attributed to slower water diffusion caused by a disorganized morphology in the sulfonated ethylene vinyl alcohol. (c) 2005 Elsevier Ltd. All rights reserved.